Joule-Thomson Effect

Definition - What does Joule-Thomson Effect mean?

Joule-Thomson Effect is the temperature change of liquids or gases when they are forced through a porous plug or valve which is kept insulated without the transfer of heat or production of work. This procedure is known as Joule-Thomson process or throttling process. All the gases except helium, neon and hydrogen cool at room temperature upon the expansion by the throttling process. These three gases can experience a similar effect but at lower temperatures only.

Petropedia explains Joule-Thomson Effect

The Joule-Thomson effect is also known as Joule-Thomson expansion, Kelvin-Joule effect and Joule-Kelvin effect and it describes the decrease or increase in the temperature of gases or liquids. It is an isenthalpic process which means the enthalpy of the fluids is kept constant during the process. The throttling process is a fundamentally irreversible process which is usually exploited in various thermal machines like heat pumps, liquefiers, refrigerators and air conditioners. It is considered as the source of losses which limits the process if it takes place because of the heat exchangers, regenerators, flow resistance and various other components of the thermal machines.